Support named capture groups in regex transformers (#94)

CHANGELOG.md

@@ -26,6 +26,7 @@ ambiguous situations.
 - Generic `ilias-web` crawler and `ilias-web` CLI command
 - Support for the course overview page. Using this URL as a target might cause
   duplication warnings, as subgroups are listed separately.
+- Support for named capture groups in regex transforms
 
 ### Fixed
 - Normalization of meeting names in cards

CONFIG.md

@@ -394,7 +394,8 @@ matches `SOURCE`, the output path is created using `TARGET` as template.
 be referred to as `{g<n>}` (e.g. `{g3}`). `{g0}` refers to the original path.
 If capturing group *n*'s contents are a valid integer, the integer value is
 available as `{i<n>}` (e.g. `{i3}`). If capturing group *n*'s contents are a
-valid float, the float value is available as `{f<n>}` (e.g. `{f3}`). If a
+valid float, the float value is available as `{f<n>}` (e.g. `{f3}`). Named capture
+groups (e.g. `(?P<name>)`) are available by their name (e.g. `{name}`). If a
 capturing group is not present (e.g. when matching the string `cd` with the
 regex `(ab)?cd`), the corresponding variables are not defined.
 

PFERD/transformer.py

@@ -110,6 +110,10 @@ class ExactReTf(Transformation):
             except ValueError:
                 pass
 
+        named_groups: Dict[str, str] = match.groupdict()
+        for name, capture in named_groups.items():
+            locals_dir[name] = capture
+
         result = eval(f"f{right!r}", {}, locals_dir)
         return Transformed(PurePath(result))